From: Avi Kivity <avi@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Anthony Liguori <anthony@codemonkey.ws>,
Rusty Russell <rusty@rustcorp.com.au>,
kvm@vger.kernel.org
Subject: Re: [PATCH, RFC] virtio_blk: add cache flush command
Date: Mon, 11 May 2009 18:45:50 +0300 [thread overview]
Message-ID: <4A08482E.30100@redhat.com> (raw)
In-Reply-To: <20090511154046.GA4226@lst.de>
Christoph Hellwig wrote:
>> If the backend implementation of T_FLUSH is fsync, I would think that
>> this would result in rather poor performance for O_DIRECT operations in
>> the guest.
>>
>
> Right now it's fsync. By the time I'll submit the backend change it
> will still be fsync, but at least called from the posix-aio-compat
> thread pool.
>
I think if we have cache=writeback we should ignore this. The user is
saying, I don't care about data loss, make the thing go fast.
For cache=none and cache=writethrough we don't really need fsync, but we
do need to flush the inflight commands.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2009-05-11 15:45 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-11 8:39 [PATCH, RFC] virtio_blk: add cache flush command Christoph Hellwig
2009-05-11 14:51 ` Anthony Liguori
2009-05-11 15:40 ` Christoph Hellwig
2009-05-11 15:45 ` Avi Kivity [this message]
2009-05-11 16:28 ` Christoph Hellwig
2009-05-11 16:49 ` Avi Kivity
2009-05-11 17:47 ` Anthony Liguori
2009-05-11 18:00 ` Avi Kivity
2009-05-11 18:29 ` Anthony Liguori
2009-05-11 18:40 ` Avi Kivity
2009-05-18 12:03 ` Christoph Hellwig
2009-05-12 7:23 ` Christoph Hellwig
2009-05-12 7:19 ` Christoph Hellwig
2009-05-12 8:35 ` Avi Kivity
2009-05-18 12:06 ` Christoph Hellwig
2009-05-11 16:38 ` Anthony Liguori
2009-05-12 7:26 ` Christoph Hellwig
2009-05-12 13:54 ` Rusty Russell
2009-05-12 14:18 ` Christian Borntraeger
2009-05-13 1:52 ` Rusty Russell
2009-05-18 12:07 ` Christoph Hellwig
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